Hi, I’m a high school student and I’m doing a
science project. My question is: How Different pH
levels of water affects the growth of plants?

Question Date: 2018-02-21

Answer 1:

The pH (acidity or basicity) level in organisms
is generally an extremely important factor for
growth. The reason that many organisms must
maintain a near-constant level of pH is that life
requires chemical reactions, and many
chemical reactions in live organisms require
certain pH levels in order to have the appropriate
charges. For instance, the making of
proteins requires the transfer of electrons,
protons, and entire portions of molecules, which
can only happen if the charges in different parts
of protein-making machinery match. When the pH in
an organism is disturbed too much, the organism
cannot make molecules that it needs to live, so it
dies. It logically follows (since plants are
organisms) that plants will die if the pH of
the water they're given is always too high or too
low compared to what they need.

If the pH differs from ideal conditions by a
certain amount, but not enough to kill the plant,
then the plant's growth will be stunted, meaning
that given the same amount of other nutrients and
sunlight, it will grow much slower, mature much
later, or not reach maturity, and this is readily
testable with some seeds and a few planters!

Answer 2:

You need to set up an experiment, where you take
plants, subject them to different pH levels
in the
water, and observe what happens. This is how
science is done, and is what makes science
different from other fields of endeavor: we don't
just read our answers from a book, because
oftentimes the book of answers isn't written yet,
so you need to write it yourself.

I'd suggest using plants that grow very
quickly.
Grass seed that you can buy in a nursery will do.
You also need different pHs of water to give them.
I'd suggest maybe a water-vinegar mixture for low
pH, pure water for neutral pH, and water with
baking soda dissolved in it for high pH (don't mix
the baking soda and the vinegar, or you will get a
frothy eruption as the acid and base react and
carbon dioxide bubbles off). Vinegar and baking
soda are both available at any supermarket. You
need to measure the concentration of the vinegar
or baking soda in the water that you use, and
preferably have some kind of pH meter that
you can
use to know exactly what the pH you are using in
each treatment (i.e. acid, neutral, alkaline).

If
you're feeling really ambitious, you could try
with different amounts of vinegar or baking soda
in the water to have different levels of acid or
basic pH. You could even do a large sample size
with multiple copies of each treatment so that you
can distinguish between the effect of pH and
random chance, but that is probably beyond what
you need for a high school project.

Answer 3:

The pH of soils can absolutely affect the
growth of plants. Too acidic of soil and too
alkaline of soil can have adverse effects on
growth. The optimal range for most plans if about
5.5 to 7pH. Too high or too low of a pH can affect
nutrient availability and the concentrations of
certain minerals that are harmful to plants.

Answer 4:

This is a really interesting question because
it turns out that pH plays a few important
roles in plant growth.

Generally, plants absorb nutrients better
in slightly acidic soils and with more nutrients
plants can grow more. Also, nitrifying
bacteria (microorganisms that break down
unusable ammonia into usable nitrates) survive
best in acidic soils . Plants need these
nitrifying bacteria because the nitrates that they
release are essential for plant growth. Overall,
plants generally survive and grow best when placed
in slightly acidic soils but that can differ
depending on the species of plant. For example,
asparagus actually grow best in neutral or
slightly basic soil , but they are the
exception rather than the rule. Thank you for
your question!